The invention relates to an apparatus for adjusting the pitch angle of a rotor blade of a wind energy installation, having a flexible envelope drive train which can be moved by a drive wheel and via which the rotor blade can be rotated in opposite directions about its longitudinal axis.
Wind energy installations are known to be equipped with apparatuses for rotor blade adjustment, in order to match the power of the installations to the wind conditions, in particular to limit their power when the wind is strong. Apparatuses are used both for individual and for joint adjustment of the rotor blades.
DE 42 21 783 C2 discloses an apparatus of the latter type which has the features mentioned initially and in which a closed toothed belt is used as an envelope drive train, which loops around the rotor blade and engages in an external tooth system formed on the rotor blade. The external tooth system is arranged at the side, adjacent to a rotating bearing which connects the rotor blade to the rotor hub. Said toothed belt is rotated through 90° and, furthermore, is deflected through 90° by a roller, such that it engages with a toothed pulley wheel which is seated on a shaft parallel to the rotor rotation axis.